This invention relates to imaging of the internal structure of a body and, more particularly, to an apparatus and method for obtaining images of cross-sections through a body.
In conventional tomography, the objective is typically to obtain an image of one or more cross-sections or planes of the internal structure of a body by combining information from a number of images obtained at different rotational perspectives to obtain a single processed image for each cross-section. Typically, the multiple images are processed and added by computer or photographically to obtain an ultimately processed single image. The procedure can then be repeated for other cross-sections or planes within the body.
It is known that a series of fluoroscopic images can be viewed to visualize the progress of a bolus of contrast material through a blood vessel of interest. Radiographic contrast agents are used to create a large difference in x-ray absorption behavior where little or none previously existed. Blood vessels are virtually invisible on fluoroscopic images (except in the chest) becuase blood, muscle, fat and soft tissue all possess similar x-ray absortpion behavior. Radiographic contrast agents contain material which has x-ray absorption properties dissimilar to blood, muscle, fat and the soft tissue. For example, when a bolus of iodinated liquid contrast material is injected into an artery or vein, the vascular structure is given artificially higher contrast on an x-ray image while the contrast material is present within a certain vascular segment.
Recently, various techniques have been developed for processing fluoroscopic images, such as with temporal filters to obtain improved images. However even these improved images can have limited usefulness in certain applications, such as where confusing overlying vasculature or other anatomy restricts the view. In such cases a cross sectional view is often necessary or desirable.
It is among the objects of the present invention to provide images of body cross-sections by a type of fluoroscopic tomography which presents, in real time, a sequence of video frames representative of a body plane of interest. It is also among the objects of the present invention to provide an apparatus and technique whereby sequences of processed images representative of different planes of interest in the body can be presented, without the need for submitting a patient to a new sequence of exposures for each plane to be presented. It is also among the objects of the present invention to employ fluoroscopic imaging and processing techniques in a tomographic type of system to obtain advantages over existing tomographic and fluoroscopic techniques.